You cannot have common cold continuously for 8years. It seems you are suffering from perennial nasal allergy. Get a routine blood test done along with absolute eosinophil count &
TSH. Get a CT scan of nose and paranasal sinuses done. If there is only allergic changes, intra nasal steroid spray and anti-allergics by mouth will help you. If there are polyps or any sinus pathology you will require surgery.